Chiral amines are ubiquitous in nature. They are common structural units in many important bioactive molecules, both synthetic and natural in origin. Chiral amines are a common structural motif in many drugs. Many chiral amines are also important chiral auxiliaries and chiral selectors. Therefore, the preparation of chiral amines is of significant economic importance.
At present, chiral amines are mainly prepared by means of chemical reduction, and amines with optical activity are prepared by using prochiral ketones. Catalyzed by Pd/C and quinine, a prochiral ketone reacts with formic acid and an ammonia or an organic primary amine to generate a chiral amine. Other researchers obtained a chiral amine through asymmetric amination and reduction of a prochiral ketone using a ruthenium complex as a catalyst (Renat Kadyrov et al. Highly Enantioselective Hydrogen-Transfer Reductive Amination: Catalytic Asymmetric Synthesis of Primary Amines. Angewandte Chemie International Edition. 2003, 42 (44), Page 5472 to Page 5474). The metal catalyst in such a reaction is a very critical factor and demands strict requirements on the metal catalyst. Also, it is necessary to carry out the reaction at high temperature and there are high requirements on operation devices. Additionally, the metal catalyst is expensive and an environmental pollutant (Ohkuma T et al. Trans-RuH (eta1-BH4) (binap) (1,2-diamine): a catalyst for asymmetric hydrogenation of simple ketones under base-free conditions. Journal of the American Chemical Society. 2002, 124(23), Page 6508 to Page 6509).
An aminotransferase, also known as a transaminase, may catalyze an exchange process between amino and carbonyl groups of alpha-amino acids. An omega-transaminase is a transaminase capable of catalysing a transamination reaction using substrates other than alpha-amino acid. Omega-transaminase may effectively produce a chiral amine through stereoselective transamination using a variety of ketones as raw materials. The omega-transaminase has attracted more and more attention by researchers because of its use of relatively cheap substrates and its ability to produce highly pure products. It is expected that the potential of omega-transaminase can be fully applied toward the industrial production of chiral amines. However, there is still a need for further research and invention of this class of enzyme.
There is a demand for an omega-transaminase with high catalytic activity and stereoselectivity toward the R-configuration so that demand for chiral amine can be satisfied.